Research Articles

Heat efficiency of a solar trough receiver with a hot mirror compared to a selective coating

Marie C. Cyulinyana, Phil Ferrer
South African Journal of Science | Vol 107, No 11/12 | a524 | DOI: https://doi.org/10.4102/sajs.v107i11/12.524 | © 2011 Marie C. Cyulinyana, Phil Ferrer | This work is licensed under CC Attribution 4.0
Submitted: 16 November 2010 | Published: 02 November 2011

About the author(s)

Marie C. Cyulinyana, Centre for Theoretical Physics, School of Physics, University of the Witwatersrand, South Africa
Phil Ferrer, Centre for Theoretical Physics, School of Physics, University of the Witwatersrand, South Africa


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Abstract

In this article, we present a solar trough system in which the receiver pipe is enclosed in a glass cover under vacuum. The dominant radiation losses from the receiver are reduced by the use of a ‘hot mirror’ on the glass cover instead of a selective coating on the receiver pipe. We present the results for a general heat transfer model and compare the performance of a selective coating with that of a hot mirror, using simulations. We determined that a hot mirror is a viable alternative to a selective coating, and certainly allows higher temperatures of the working fluid. We recommend the use of a hybrid system, in which a selective coating is used in the part of the receiver pipe in the low temperature region, and a hot mirror is used in the high temperature region to reduce radiation losses.

Keywords

solar trough; selective coating; hot mirror; efficiency; receiver coating

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